Hitherto, glufosinate and its salts are used for the purpose of controlling weeds. However, a crop injury caused by glufosinate or its salts is occasionally a problem (see Patent Document 1).
A herbicidal composition comprising glufosinate or its salts and a PPO inhibitor is known to have a synergistic herbicidal activity (see Patent Document 2-6). These documents, however, do not disclose less than 1/2,000 as a weight ratio of the PPO inhibitor to glufosinate or its salt.